One of my column is defined as ntext datatype which is no longer supported by many streams. I'm trying my best to convert that column to numeric or int and every attempt is reaching anywhere.
reg_no #my ntext field | name | country | etc |
I tried to alter the col using the command we all use, but failed
alter table tabl1
alter column [reg_no] numeric(38,0)
Error:
Error converting data type nvarchar to numeric
Any suggestions on fixing this or has anyone come across this in the past, if yes how did you get over it
You should be able to do this in two steps:
alter table tabl1 alter column [reg_no] nvarchar(max);
alter table tabl1 alter column [reg_no] numeric(38,0);
ntext is deprecated and conversion to numeric is not supported, but converting to nvarchar() is supported.
This assumes that the values are compatible with numeric. Otherwise you will get a type conversion error. If this happens, you can get the offending values by using:
select *
from t
where try_convert(numeric(38, 0), try_convert(nvarchar(max), x)) is null
Try,
select convert(int,convcert(varchar(40), reg_no)) as newfieldname from tabl1
Related
I am trying to change a column's datatype. The column of type VARCHAR has thousands of GUID values like look those shown below:
b1f4ff32-48d4-494e-a32c-044014cea9
bc5a1158-b310-49ff-a1f3-09d4f8707f69
4b7ebc9d-9fa1-42d9-811e-0b7b4b7297a
fc7ba848-98ea-4bc6-add7-11f0ee9c6917a21
485741ff-2ab2-4705-91b3-136389948b7c
I need to convert the column type to unqiqueidentifier using the script below. Can I do that safely without corrupting the column data?
alter table MyTable
alter column guidColumn uniqueidentifier not null
If you change the data type SQL Server will first check if all the values in the columns can be implicitly converted to the new data type; if they cannot then the ALTER will fail. If they can, then they will be implicitly converted and the ALTER will be successful (assuming no dependencies of course).
For a uniqueidentifier then either it's a valid value or it's not, so either the data will all convert or the ALTER won't take place. For something like a date and time data type, however, you could very easily end up with incorrect data if the data is stored in an ambiguous format like dd/MM/yyyy. This could mean a value like '12/05/2022' ends up being stored as the date value 2022-12-05 rather than 2022-05-12. For such scenarios you would therefore want to UPDATE the data to an unambiguous format first, and then ALTER the data type of the column.
The uniqueidentifier type is considered a character type for the purposes of conversion from a character expression, and therefore is subject to the truncation rules for converting to a character type.
Also there are limitations, uniqueidentifier type is limited to 36 char
So if you decide to truncate the table like in this example:
DECLARE #ID NVARCHAR(max) = N'0E984725-C51C-4BF4-9960-E1C80E27ABA0wrong';
SELECT #ID, CONVERT(uniqueidentifier, #ID) AS TruncatedValue;
This will be the result:
String
Truncated Value
0E984725-C51C-4BF4-9960-E1C80E27ABA0wrong
0E984725-C51C-4BF4-9960-E1C80E27ABA0
So, if your string is more or less than 36 it will not truncate correctly.
For more information check Microsoft documentation:
https://learn.microsoft.com/en-us/sql/t-sql/data-types/uniqueidentifier-transact-sql?view=sql-server-ver15
I am trying to convert data type of one of my columns (the table was imported from Excel), and then it shows an error
Error converting data type nvarchar to float
Code:
ALTER TABLE [dbo].[games_activity_2020$]
ALTER COLUMN [Version] float
What can I do differently?
probably there might be any character values inserted in the table while importing from excel. You can check those values using the below query
SELECT version
from [dbo].[games_activity_2020$]
where TRY_CONVERT(float, version) IS NULL
you can update those values and try to ALTER the table again
I suggest you run
SELECT * FROM [dbo].[games_activity_2020$]
WHERE TRY_CAST([Version] as FLOAT) IS NULL
and fix up any problematic values
I have a column datedocumented in the format YYYYMMDD and of the datatype nvarchar. I want to change the data type to datetime and update the column name exdatedocumented and alter the table using ALTER .can anyone help in this.I have tried something like this
update dbo.table2
set [DateDocumented] = convert(datetime,CAST([DateDocumented] as datetime),130)
I ended up getting error
Msg 242, Level 16, State 3, Line 1
The conversion of a nvarchar data type to a datetime data type resulted in an out-of-range value.
The statement has been terminated
.
You should be able to just change the column type:
alter dbo.table2 alter column DateDocumented datetime;
Your column is in a format suitable for conversion. If you wanted to use default formats instead, just do:
update table dbo.table2
set [DateDocumented] = convert(datetime, CAST([DateDocumented] as datetime));
This should also allow the column to be converted to a datetime.
1st change that column name then alter table
sp_RENAME 'dbo.table2.datedocumented', 'exdatedocumented' , 'COLUMN'
go
ALTER TABLE dbo.table2
ALTER COLUMN exdatedocumented datetime;
It seems we have two things going on here. Changing the type for a column. And changing the name for a column. Let's try to keep these separate so not to confuse things. I will adress the changing of type (from varchar to datetime):
First of all: Why datetime? Why note datetime2 (with whatever fractions of seconds you want, for instance datetime2(0))? The new types for date and time has been around for 10 years now!
Anyhow, you apparently have values in your table which are not valid dates! First thing you need to do is to find those rows and handle them. Lets say that you will change to datetime2(0), if not, then just change below to datetime instead:
SELECT *
FROM dbo.Table2
WHERE TRY_CAST(DateDocumented AS datetime2(0)) IS NULL
I am trying to convert a column formatted in varchar to decimal(19,12) with the following line of code
ALTER TABLE [tablename]
ALTER COLUMN [columnname][format]
and get the following prompt:
Msg 8114, Level 16, State 5, Line 25
Error converting data type varchar to numeric.
Has worked before like a charm. The issue here seems to be that the values in the column are 19 or so digit numeric values formatted as text.
I tried to create a new column, pasted shortened cell values (used the left() function) into it from the original column but that doesn't seem to do the trick either since the code above ends up occationally with the additional "Arithmetic overflow occurred." message.
When some of the rows have incorrect values, ALTER COLUMN would not work. A typical course of action goes like this:
Add a new column of the desired type
Update the column with values that you would like to keep
Drop the old column
Rename the new column
Step 2 would go like this:
UPDATE MyTable
SET NewColumn =
CASE WHEN ISNUMERIC(OldColumn)=1 AND DATALENGTH(OldColumn) <= 19 THEN
CAST(OldColumn AS decimal(19,12))
ELSE
NULL
END
You could also turn ANSI warnings off with SET ANSI_WARNINGS OFF command, which would let you run ALTER COLUMN ignoring data trunction errors. The drawback of this approach is that potential errors get ignored. On the other hand, when you do conversion explicitly with a CASE expression you have an option to supply an alternative value for the error case (I used NULL above, but you can put any number you want).
Could you try to seperate your problem? This does work on SQL 2012:
set nocount on
if object_id ('tempdb..#t1') is not null drop table #t1
create table #t1 (c1 varchar(100))
insert #t1 values ('1234567.8901234567890')
select * from #t1
alter table #t1
alter column c1 decimal(19,12)
select * from #t1
If you play around a bit with the strings you easily can produce an arimetic overflow error. But 'Error converting data type varchar to numeric' needs character or empty sting.
Maybe you can try with your data?
I have a database table of that I have used to store the data returned from a web spider. I have a column that contains ticket prices for different events all in the varchar type (as the scrapy spider has to scrape the data in unicode). I'm trying to return the min price of the column and since the min() function only works for data of type INT, I tried to convert the column to integers using a solution from this SO post:
ALTER TABLE vs_tickets ALTER COLUMN ticketprice TYPE integer USING (ticketprice::integer);
but I got the error: ERROR: invalid input syntax for integer:
I also tried: change_column :vs_tickets, :ticketprice, 'integer USING CAST(ticketprice AS integer)' but that didn't work either.
What is the proper way to convert the column to type INT?
Edit:
You have decimal places in the string, so a simple cast is not going to work. You can do a double conversion:
cast(cast(ticketprice as decimal(10, 2)) as int)
or:
(ticketprice::decimal(10, 2))::int
(The parens are not strictly necessary.)
EDIT:
Or, as Erwin points out, just use numeric:
(ticketprice::numeric)::int
Postgres is much smarter about numeric than most other databases . . . after all, it supports numbers that are egregiously large ;)
The final query is:
ALTER TABLE vs_tickets
ALTER COLUMN ticketprice TYPE integer USING (ticketprice::numeric::integer);
I'm going to bet on your column have wrong characters.
Also you may want use float or numeric because you will lose decimals if convert to integers.
You need create a function to check if a text is numeric like this isnumeric-with-postgresql
Then check each row like this
select ticketprice
from vs_tickets
where ISNUMERIC(ticketprice) = false;
As your comment you also should try
SELECT ticketprice::float
You will be best off adding an INT column, moving your data with a cast and then removing the old varchar column.
ALTER TABLE vs_tickets ADD COLUMN ticketprice_int TYPE int;
GO
update vs_tickets SET ticketprice_int = cast(ticketprice as int);
// if you fail to cast the varchar to int you can use Gordon's method
// update vs_tickets SET ticketprice_int = cast(cast(ticketprice as decimal(10, 2)) as int);
GO
ALTER TABLE vs_tickets DROP COLUMN ticketprice;
GO
ALTER TABLE vs_tickets RENAME COLUMN ticketprice_int to ticketprice;
GO
With this at minimum you will be able to tell if and where a cast/convert fails and be able to check and recheck at each step before you can't turn back.